Hydrogen has been attracting attention as an energy source capable of restraining emission of carbon dioxide. There is a possibility, however, that if hydrogen gas leaks out into the surrounding atmosphere (e.g., an area around a hydrogen gas generation apparatus or hydrogen gas storage apparatus, or a parking lot where motor vehicles using hydrogen as fuel are parked), explosion will be caused. It is therefore necessary that leakage of hydrogen gas should be immediately detected and stopped.
To meet the needs, a hydrogen gas detection device has been contrived in which leakage hydrogen gas is detected by a hydrogen sensor heated by a heater. Hydrogen gas detection devices of this type are disclosed, for example, in Unexamined Japanese Patent Publications No. 2003-098147 and No. 2004-144564.
However, the hydrogen sensors used in these hydrogen gas detection devices cannot detect hydrogen unless they are heated to a high temperature of several hundred degrees Celsius. Thus, the possibility of a hydrogen gas explosion being induced by heat cannot be negated, making it necessary to take measures to prevent such explosion from being caused by the high-temperature heating.
Also, with the above hydrogen gas detection device, although leakage hydrogen gas present around the hydrogen sensor can be detected, it is not possible to detect leakage hydrogen gas over a wide area (space).